Soil persistence studies with bromoxynil, propanil and [14C]dicamba in herbicidal mixtures

The persistence of bromoxynil (3,5-dibromo-4-hydroxybenzonitrile), [¹⁴C]dicamba (3,6-dichloro-2-methoxybenzoic-7-¹⁴C acid) and propanil [N-(3,4-dichlorophenyl)propionamide] at rates equivalent to 1 kg ha^?1, were studied under laboratory conditions in a clay loam, a heavy clay and a sandy loam at 85% of field capacity and at 20±1°C, both singly and in the presence of herbicides normally applied with these chemicals as tank-mix or split-mix components. The degradation of bromoxynil was rapid with over 90% breakdown occurring within a week in the heavy clay and sandy-loam soils, while in the clay-loam approximately 80% of the bromoxynil had broken down after 7 days. In all three soils degradation was unaffected by the presence of asulam, diclofop-methyl, flamprop-methyl, MCPA, metribuzin or propanil. Propanil underwent rapid degradation in all soil treatments, with over 95% of the applied propanil being dissipated within 7 days. There were no noticeable effects on propanil degradation resulting from applications of asulam, barban, bromoxynil, dicamba, MCPA, MCPB, metribuzin or 2,4-D. The breakdown of [¹⁴C]dicamba in a particular soil was unaffected by being applied alone or in the presence of diclofop-methyl, flampropmethyl, MCPA, metribuzin, propanil or 2,4-D. The times for 50% of the applied dicamba to be degraded were approximately 16 days in both the clay loam and sandy loam, and about 50 days in the heavy clay.     

Mechanical Properties of Four Suture Patterns for Transected Equine Tendon Repair

Thirty-six superficial digital flexor tendons from nine fresh equine cadavers were transected and sutured with size 2 monofilament nylon. Nine tendons were repaired with each of four suture patterns: single-locking loop, double-locking loop, triple-locking loop, or three-loop pulley. The times required for application, tensile strengths, resistance to distraction (gap), and modes of failure were analyzed. The mean times required were: single-locking loop, 3 mins, 15 secs; double-locking loop, 4 mins, 15 secs; triple-locking loop, 10 mins, 50 secs; and three-loop pulley, 4 mins. The double-locking loop, triple-locking loop, and three-loop pulley suture patterns were stronger than the single-locking loop. The triple-locking loop and three-loop pulley patterns were close in strength and only the triple-locking loop was stronger than the double-locking loop. The three-loop pulley had the greatest resistance to gap formation and its mode of failure was different from the others. The three-locking loop suture patterns failed by suture breakage but the three-loop pulley failed first by suture pull-out and then by suture breakage.     

Net production of herbage from a continuously stocked Lolium perenne-dominated sward in late autumn

Preliminary studies were carried out on the effect of stocking rate during late autumn on a continuously stocked Lolium perenne -dominated sward at an upland site in central Scotland. Measurements were made of L. perenne tiller population density on 29 September and 2 November and of L. perenne net production, mean sward height and total herbage mass in early and late October and early and late November. Stocking rates were 12 ewes per ha during October and 8 and 16 ewes per ha during November. Sward height and herbage mass declined with time and more rapidly at the higher stocking rate. L. perenne growth per tiller and per unit area was influenced by time but not by stocking rate and was closely related to the 5·5°C soil temperature at 10 cm depth. Tiller senescence was greatly reduced at the higher stocking rate and/or the consequentially lower sward height and herbage mass. Tiller net production was therefore sustained at a positive level on the higher stocked sward throughout November while on the lower stocked sward it fell below zero early in November.     

The use of intrathecal analgesia and contrast radiography as preoperative diagnostic methods for digital flexor tendon sheath pathology

Reasons for performing study: The sensitivity of ultrasonography for the diagnosis of manica flexoria (MF) tears within the digital flexor tendon sheath (DFTS) is lower than for diagnosis of marginal tears of the deep digital flexor tendon (DDFT). Additional diagnostic tools would assist in appropriate decision making for either conservative or surgical management. Objectives: To evaluate the improvement in lameness of horses with MF or DDFT tears following intrathecal analgesia and to assess the sensitivity and specificity of contrast radiography for the diagnosis of these tears. Methods: The case records of horses presented to a referral clinic over a 7‐year period that underwent intrathecal diagnostic analgesia, or intrathecal analgesia and contrast radiography, of the DFTS with subsequent tenoscopy were examined. Results: Fifty‐three limbs had intrathecal diagnostic analgesia performed and 23 contrast tenograms were assessed in horses undergoing DFTS tenoscopy. Horses with DDFT tears were significantly more likely to respond positively to intrathecal diagnostic analgesia than those with MF tears (P = 0.02). Using contrast radiography, tears of the MF were predicted with an overall sensitivity of 96% and specificity of 80%; marginal tears of the DDFT were predicted with an overall sensitivity of 57% and specificity of 84%. Conclusions: The results of intrathecal analgesia of the DFTS in combination with contrast radiography have a high sensitivity for predicting MF tears. The sensitivity of contrast radiography for predicting tears of the DDFT is lower but the specificity remains high. Potential relevance: Contrast radiography performed at the same time as intrathecal analgesia provides useful information regarding the presence of MF tears and DDFT tears, which can assist in the decision of whether to manage the lameness conservatively or with tenoscopic evaluation.     

Cardiovascular effects of the macrolide antibiotic tilmicosin, administered alone and in combination with propranolol or dobutamine, in conscious unrestrained dogs

Tilmicosin(TM), a macrolide antibiotic and active ingredient in formulated Micotil 300^TM (Eli Lilly and Co., Indianapolis, IN, USA), is the active ingredient in a formulated animal product used for the treatment of respiratory tract infections in cattle. Owing to the concern of governmental regulatory agencies over the possibility of an accidental injection of the antibiotic to a livestock handler, the cardiovascular effects of sub lethal doses of TM were evaluated in conscious mixed-breed dogs. Left ventricular function, systemic arterial blood pressure, and heart rate (HR) responses to TM alone and in combination with propranolol(P) or dobutamine HCl(DOB) were evaluated. Dogs were instrumented with indwelling micromanometers implanted in the left ventricular chamber and in the thoracic aorta. Cardiovascular variables were recorded, and the peak value of the first derivative of left ventricular pressure (dp/dt_(max)) was used as an index of left ventricular inotropic state. Six treatments were randomly assigned to each of the six dogs using a Latin square design. The six treatments were vehicle, TM alone (2.5 mg/kg of body weight), TM immediately followed by P. and TM immediately followed by 1 of 3 dosages of DOB infused for ?45 min. Additionally, doses of TM alone (0.25, 1.0, 2.5, and 5.0 mg/kg) were administered to complete a dose-response curve. TM caused dose dependent decreases in (dp/dt_(max)) and aortic pulse pressure. HR increased dose-dependently. Left ventricular end-diastolic pressure increased at the 2.5 and 5.0 mg/kg dosages. Left ventricular systolic pressure was reduced dose-dependently at the 2.5 and 5.0 mg/kg dosages. Treatment with P exacerbated the negative inotropic effect and the decrease in left ventricular systolic pressure, but did not attenuate the tachycardia associated with TM treatment. DOB attenuated the changes in ventricular inotropic state in a dose-dependent manner. DOB infusion also restored left ventricular systolic pressure at dosages of 3 or 10 μg/min/kg. Our data indicate that toxic doses of TM may have a negative inotropic effect in conscious dogs. HR increased in a dose-dependent manner and was not the result of β₁-receptor stimulation. DOB reversed some, but not all, of the effects caused by TM administration.     

THE HYDROLYSIS OF 2,4-DICHLOROPHENOXY- ACETATE ESTERS TO 2,4-DICHLOROPHENOXYACETIC ACID IN SASKATCHEWAN SOILS

Summary. The hydrolysis of the iso-propyl, n-butyl and iso-octyl esters of 2,4-dichloro-phenoxyacetic acid to the free acid was studied in aqueous solutions and on three prairie soils. The esters were analysed using electron-capture gas chromatography following extraction from solution with benzene, and from soils, using either 10% aqueous aceto-nitrile or a 2:1 mixture of benzene and iso-propanol.
Ester hydrolysis in 0·1 n sodium hydroxide solution was very rapid, more than 50% of all the esters being hydrolysed in less than 1 min. In 0·1 n sodium carbonate solution the times for 50% hydrolysis at 25°C were < 5, 5 and 30 min for the n-butyl, iso-propyl and iso-octyl esters respectively. In distilled water negligible hydrolysis occurred over a 5 h period.
The iso-propyl and n-butyl esters underwent a very facile hydrolysis on soils. Shaking the treated soils with 0·1 M calcium chloride solution for 30 min at 25°C resulted in extensive hydrolysis to the acid as determined spectrophotometrically. Under similar conditions negligible hydrolysis of the iso-octyl ester occurred.
After 1·5 h at 25±1°C on soils at their wilting point moisture levels, and greater, less than 15% of the applied iso-propyl or n-butyl esters could be recovered using either extraction procedure, indicating rapid hydrolysis to the acid. After 24 h no iso-propyl or n-butyl ester residues could be detected in any of the soils. Loss of the iso-octyl ester was slower under these conditions with approximately 20–30% of the ester remaining after 24 h, and 10% after 48 h.
L'hydrolyse des esters de 2,4 dichlorophénoxyacétates en acide 2,4 dichlorophénoxyacétique dans les sols du saskatchewan.     

External Fixator Clamp Reuse Degrades Clamp Mechanical Performance

Objective— To determine the effects of clamp reuse for the Kirschner–Ehmer (KE); Securos; and the IMEX–SK clamp.
Study Design— Experimental bench test of mechanical properties.
Methods— Specially designed fixtures were used to mechanically test 18 clamps of each type with respect to 6 mechanical variables: fixator pin slippage, connecting bar slippage, fixator pin rotation, connecting bar rotation, and clockwise and counterclockwise clamp–bolt axis pivot. Each clamp was tested 6 times for each variable at 7.68 Nm of clamp–bolt tightening torque. Results were compared using repeated measures ANOVA.
Results— For the IMEX–SK clamp, a significant degradation in the force required to cause slippage was found for connecting bar slippage and fixator pin rotation; however, this clamp also had a significant increase in the force to initiate slippage for clockwise clamp–bolt axis pivot with reuse. The Securos clamp had significant degradation in connecting bar slippage, connecting bar rotation, and fixator pin rotation whereas the KE clamp had significant degradation in connecting bar slippage only.
Conclusions— All 3 external fixator clamp types degraded in 1 or more movement variables in their ability to resist motion with reuse. The IMEX and Securos clamps were more subject to degradation than the KE clamp and this may have clinical importance for fixator composite rigidity.
Clinical Relevance— Fracture-reduction stability is related to the ability to resist motion within a clamp. The unpredictable nature of degradation we found cautions against repeated use. Clinicians should consider reuse of external fixator clamps with the knowledge that repeated use degrades clamp mechanical performance.     

An assessment of cereal grains and other starch sources in diets for barramundi (Lates calcarifer) – implications for nutritional and functional qualities of extruded feeds

This study examined the digestibilities of whole diets and ingredients of a range of starch/cereal grains when fed to barramundi (Lates calcarifer). The ingredients included wheat, oats, sorghum, triticale, barley, among others. Twelve diets were prepared using a twin‐screw extruder to mimic modern aquafeed‐manufacturing processes. The diets were then fed to juvenile barramundi and the faeces collected using stripping methods. Significant variability in the digestible energy and starch value was seen among the test ingredients and diets. Diet starch digestibility ranged from 49.1% to 93.9%. Ingredient starch digestibility ranged from 18.0% to 96.5%. Among the different starch ingredients, a strong negative correlation between the ingredient amylopectin content and starch digestibility of that ingredient was observed. This relationship was also mirrored by a similar relationship, although not as strong, between total starch and starch digestibility. This study demonstrates that barramundi have limited ability to digest starch and that there is an effect of inclusion level on the ability of the animal to digest this nutrient. But it also demonstrates that there is a wide range of cereal sources that can be effectively used as starch sources in extruded diets for this species.     

The role of river flow in the migration of adult Atlantic salmon,Salmo salar,through estuaries and rivers

An assumption of Atlantic salmon, Salmo salar L., management is that river flow influences their upstream migration; but the quantitative relationships between flow and movements are variable and inconsistent. A consensus has emerged that standard rules on salmon flow needs for water management across all rivers are unattainable. However, this does not preclude an underlying conceptual framework that should guide a consistent scientific basis to flow management for protecting salmon. This article examines the potential for a conceptual framework from a British Isles perspective, assuming that upstream migration is an emergent property from selection to optimise lifetime fitness. The template for this adaptation is the diversity of river types and hydro‐morphology in British rivers coupled with life‐history and migration adaptations that may be influenced by flow‐related factors. Models of adult salmon migration through estuaries and rivers are outlined that may provide a basis for developing generic guidance.     

Carbon and water footprints of major crop production in India

Scarcity of water and emission of greenhouse gases (GHGs) are the two key environmental issues affecting crop production in India.Reducing the carbon footprint (CF) and water footprint (WF) of crop production can help to mitigate the environmental hazards that stem from GHG emissions and water scarcity.The CFs and WFs of three major cereal crops,rice,wheat,and maize,were estimated for the year 2014 under the environmental conditions in India,based on national statistics and other data sources.To...